This invention relates to a method and apparatus for predicting destruction of a rolling bearing utilizing an acoustic emission (hereinafter referred to as AE).
For detecting the abnormal condition of a sliding bearing by utilizing AE, there has hitherto been known a method in which such abnormality is detected by an AE signal issuing from a metal surface damage caused by contact between a sleeve and a bush as a consequence of the lack of an oil film. On the other hand, in case of a rolling bearing, it has been known to detect the abnormal condition of the bearing or anticipate such possible abnormality as flaking or the like by AE signals of all frequencies or an AE signal within a frequency range of up to several 100 KHz.
However, with the known method for detecting the abnormal condition of a sliding bearing, a trouble is that since an AE from a metal surface damage is detected, it is impossible to foresee any possible damage. With the known method for anticipating the abnormality of a rolling bearing, it is difficult to make accurate anticipation with relation to abnormality such as flaking and the like, on the basis of the condition of the bearing, because AE signals of a wide frequency range are detected and no detection is made of any AE signal of such frequency range as is peculiar to damage indication. Where such abnormality as flaking or the like is anticipated by all frequency AE signals issuing from the rolling bearing according to the known method, this anticipation is not accurate and another difficulty is that critical limit determination has to be made when the operation time of the bearing has reached a level of 40-80% of possible flaking time.